Multiple transmitter units



June 15, 1948. D. L. HINGS 89 MULTIPLE TRANSMITTER UNITS Filed May 5, 1944 TAI/ENTO Dawall M Patented June 15, 1948 zguassa "'oFF-lcE MULTIPLE TRANSMITTER UNITS 7 Donald L. Rings; Ottawa, Ontario, Canada Application May 3, 1944, Serial No. 533,860 In Canada April 25,- 1944' My invention relates in general to radio transmitting systems and more particularly to individual transmitting units which may be readily and easily combined or plugged together to give added power as-well as give additionalfrequency channels.

An object of my invention is to provide for selectively operating one or a plurality of amplifying circuits from a'sing-le oscillator.

Another object of my invention is to provide for reducing the number of switch contacts and the shielding normally required between input and output circuits for channel frequency chang- Another object of my invention is to provide for connecting the cathode of the selected oscil-- lator tube in series with the cathodes of one or of the plurality of amplifier tubes for direct current and for exciting the cathodes of the amplifier tubes at radio frequency potential above ground.

Another object of myinvention is to provide for energizing the cathodes of the amplifier tubes at radio frequency from the output oscillatory circuit of the selected oscillator.

Another object of my invention is to provide for switching the cathodes on the input side of the amplifiers instead of switching the grids.

Another object of my invention is to provide in one switch having a number of contacts for switching both the input side of the amplifier as well as the output side of the amplifier and at the same time prevent electrical inter-actionwhich if allowed tion.

Another object of my invention is toarrange forcontrolling the switchingunits at a remote point:

Another object of my invention is to provide to occur may cause self oscillafor mounting a single transmitting unit in a single case having plug connections whereby one or: a pluralityof individual units may be readily replaced in case of failure of one or moreof the operating units. I,

ther objects and a fuller understanding of my invention may be had byreferring to the following description and claims taken in conjunction with the drawing in which the single figure represents a system employing three separate and individual units designated by the reference characters A, Band C. Although I have shown three individual and separate units it is to be understood that any larger number of units may be employed and still be within the scope of my invention, v f

1 Claims. (01. 250-11) The circuits for the three individual units A, B and C are substantially alike and where possible the corresponding parts are designated by the same reference characters.

In the unit A, the'oscillator tube is designated by the reference character ill, in unit B by the reference character I I and in unit C by the reference character l2. In unit A, the amplifier tube V is designated by the reference character 20, in

unit B by the reference character 2| and in unit C by the reference character 22. The transfer switch in unit A is designated by the reference character 40, in unit 13 by the reference character 4| and in unit C by the reference character 42:

The cathodes for the oscillator tubes are designated by the reference character l3 and the inductance element of the output oscillatory circuit for each of the oscillator tubes is designated by the reference character [4. The inductance elementof the output oscillatory circuits for the amplifier tubes are designated by the reference character [5. The plates l6 of all the amplifier tubes are arranged to be connected to the plate end of the selected oscillatory output'circuit l5 through the selected switch contacts 33. Thus; for example, with the switch 411 closed, all the plates l6 are connected to the oscillatory output circuit l5 for the unit A. When B is the selected unit, all of the plates are connected to the oscillatory circuit for unit B. The same is true for unit C when it is selected. The aerial or antenna end of the oscillatory circuits l5 are arranged to be connected to the antenna 29 through a common conductor 45 and the switch contact 34 of the selected switch. The plates iii are connected through a radio frequency choke 46 to high tension positive direct current potentials. The grids H of the amplifier tubes are by-passed to ground for radio frequency through capacitors 31. Each of the control grids I! are connected to a common conductor 41 which is in turn connected to a suitable source of bias and'modulation. indicated by the reference character I9. All of the filaments I8 ofthe amplifier tubes and the filament ill of the selected oscillator tube areconnected in series for direct current excitation. With the switch 4!! closed as shown in the drawing the direct current excitation for the cathodes maybe traced from the low tension positive direct current potential in the lower right hand corner of the drawing through a resistance 48, a radio frequency choke coil 49, a switch 50, the filament ll! of the tube 22, the filament I8 of the tube 2i, the filament l8 of the tube 20, the switch contact 32 to the tap 5| on the inductance coil l4 forthe 3 oscillatory output circuit of the oscillator 10, and then through the filament l3 for the oscillator tube I to the negative side of the low tension direct current source. When the switch 4| is closed, the filament l3 for the tube II is connected in series with all the cathodes ll! of the amplifier tubes and when the switch 42 is closed the filament I 3 for the tube 12 is connected in series i' an we catl'ic'i'des E8" of thaifiplifier tubes. The" filaments l8 for an the amplifier tubes are energized at radio frequency potentialsabove ground through the adjustable tap 5| 6f the selected oscillator circuit. When the unit is removed the switch 59 is closed for the unit B to complete the circuit for energizing the oath odes N3 of the units A and B. When both the units B and C are disconnected the for the unit A is closed for completing the oathode circuit for the tubes of the unit A. Thecofiductors passing between the terminals of the respective" units may be in-the form of male and female plugs asillustrated, so that the units may be readily removed and-replaced to meet the re quirements of the installation. 7 W

The transfer switches 46,- 41 and 42' are selectively and individua lly controlled by a selector switch 6:3 having a rotating contact member 6-! which selects the respective contact that, leads.

to the energizing coils ofthe respective transfer switches; energized until the carrier switch 62 is depressed;

depression of the carrier switch 62 closes a circuit for energizing theselected coil from the illustrated low tension direct current source. The switch 62- is depressed to talk -a-nd modulate the carrier wave and the opening of the switch rendersthe transmitter inoperative.

The transfer switches (ill, 4| and 42 interruptthe cathode circuits which are of low impedance and atthe same time interrupt the output circuit oithe amplifying tubes, and inasmuch the cathode circuits are of a relatively low impedance with respect toground, I am able to minimize the electrical inter-action between the input and output circuits which may tendto cause self excited oscillations. Inmy circuitarrangements the switches require no shielding between their respective-parts;

Inoperation, when the switch 40 is closed the oscillator tube A for the'unit A- is arranged to control the three am-plifying tubes for the units A, Band C. When the oscillator for the unitB is selected i-t providc-s for controlling the amplifying tubes for the three units A, 13- and C, and when the oscillator for unit C is selected it pro vides for controllingthe operation of the ampli fiers forthe three units A B and G. The three a'ihfil' as when in operation feedtheir power sate-way to the antenna 29 In actual practice the power of'an installation may e increased merely by adding an additional uriit which is a low cost method of increasi "g" tlie'power of an established station without fbiiiIdin'g it for greater power output, oar-e selected to oscillate atdifi t frequencies although it is'withinth'e' scope of my inv'e'htiontd have at least two of the units to operate at the same frequencyso that iii case one of the units fail theoth'er unit switched intoope' An eizample' of the""bility' of adding power to established installation be had by re: rants further to me seems.

a u as ijxwji'i pe i er t fl'er sections described} may be? of sinrilar' dirhe The selected transfer switch not be locally or remotely" within those sections previously in use.

sions and mounted in the same rack assembly. The power supply unit may be of like dimensions and where desirable may be mounted likewise.

Upon adding additional amplifier sections, the unit feed bus lines are carried through each unit chassis to plug terminals in such a way that the output amplifier tube terminals of all units are in series or parallel, regardless of which output circuit marge-fiance is connected get-cute system or which excitcr tube is dating the common cathodes.

In this manner, upon the addition of an amplifier unit;- for an increased overall power output, it is necessar" only to make minor realignment of the vans-me adjustment elements provided w} in erest capacity of the modulator section and power supply normally would be of ample E value to supply anticipated additional amplifier nj e cjtiri ja lstr etcar sena or c H units with an cr the amplifiers of the an an antenna, said switching means connecting che'" units. However, should this anticipated number be e; ceeded-,--then the powerand modulator units would be increased in capacityas necessary.-

' Although; haveshown and described my in ven-tion with a-certain degree ofparticularity; it understood that changes may be made thereinwithout departing from the spirit of theinventicn wh-ich'are includedwithin'the scope of claims hereinafter set forth; v

I claimas ny invention: 1*. A radio frequency transmitting system-,- comprising a plurality of transmitter unjit-sc'ach com prising an oscillator and an amplifier, plug con -f nectors. forconnecting theunits together, and transfer switching means for connecting a se, lected oscillator of any one of the units with all i of the amplifiers of theunits, an antenna; and circuitmeans for connecting the amplifiers to" the antenna:

- 2; A'radi o'frequency transmitting system, comprising a-plura-li-ty of transrr'litter units eachcomprising an oscillator and an amplifier, plug con-i nectors for connecting the units together; and transfer switching means for connecting ase,-' lected oscillator of any one of the units with all of the amplifiers of the unitsyanantenna; and circuit means for connecting the amplifiers" to the antenna; each said oscillators having a tube in cluding" aca-thode and an'outputradio frequency circuit; each said amplifier including an amphtying tube having a cathode, said transfer switch= in=g means connec'ting'the' cathode of the selected oscillator in series with all the cathodes of the amplifying tub'e's said cathodes of the amplifying tukiebeingenergized at radio fre'quen cy potentials from the output radio frequency circuit of cans for ting sedated oscillator of any due the units an" ofth'e' amplifiers of the uses, an antenna, said switching means oi'iiie'ctiiig' the i's l eia u Qilfi l i h' i l f i i I I 4 n1 enna and with all of the plates of clean;

4}. A? radio freqfie'ccy transmitter system c pr'i-s'ng' a plural'i y (if transmitter un t's'each om j f an dscil lator and an amplifier each id airipli er men-merge plate and an dscil toiy ou put circuit, and transfer switching fiieansidrfco the oscillatory output circuit of the selected unit with the antenna and with all of the plates of the amplifiers, and means for controlling the switching means at a remote point.

5. A radio frequency transmitting system comprising an antenna, a plurality of transmitter units each comprising an oscillator circuit, an amplifier circuit and an output circuit, each said oscillator circuit including at least an anode electrode and a cathode electrode operating as space discharge means, means for connecting the cathode electrode of each oscillator circuit to a point of reference potential, each said amplifier circuit including at least a cathode element and an anode element operating as space discharge means, first switch means for connecting the anode electrode of the oscillator circuit of a selected one of said units with the cathode electrodes of the amplifier circuits of all of said units and thereby exciting the said cathodes at radio frequency potential above said reference point, and second switch means for connecting the anode electrodes of the amplifier circuit of all of said units in circuit relation with the output circuit of said selected one of said units and the antenna and thereby exciting the output circuit of said selected one of said units and the antenna from all of said amplifier circuits.

6. A radio frequency transmitting system comprising an antenna, a plurality of transmitter units each comprising an oscillator circuit, an amplifier circuit and an output circuit, plug connectors for connecting the units together, each said oscillator circuit including at least an anode electrode and a cathode electrode operating as space discharge means, means for connecting the cathode electrode of each oscillator circuit to a point of reference potential, each said amplifier circuit including at least a cathode element and an anode element operating as space dischargemeans, first switch means for connecting the anode electrode of the oscillator circuit of a selected one of said units with the cathode electrodes of the amplifier circuits of all of said units and thereby exciting the said cathodes at radio frequency potential above said reference point, and second switch means for connecting 6 the anode electrodes of the amplifier circuit of all of said units in circuit relation with the output circuit of said seleceted one of said units and the antenna and thereby exciting the output circuit of said selected one of said units and the antenna from all of said amplifier circuits.

7. A radio frequency transmitting system comprising an antenna, a plurality of transmitter units each comprising an oscillator circuit, an amplifier circuit and an output circuit, each said oscillator circuit including output means, each said amplifier circuit including at least a cathode element and an anode element operating as space discharge means, first switch means for connecting the output means of a selected one of said units with the cathode electrodes of the amplifier circuits of all of said units and thereby exciting the said cathodes from said output means, and second switch means for connecting the anode electrodes of the amplifier circuit of all of said units in circuit relation with the output circuit of said selected one of said units and the antenna and thereby exciting the output circuit of said selected one of said units and the antenna from all of said amplifier circuits,

DONALD L. HINGS.

REFERENCES CITED The following references are of record in the ters, by A. G. Shefiield, February 1939, pages 35, 36, 37, 75. 

